Magneto-quantum-resistance oscillations in tunnel-coupled double quantum wells in tilted magnetic fields: Variable Landau biladders

摘要

We present a linear-response theory of magneto-quantum-resistance oscillations of the in-plane resistances R-xx and R-yy in two coupled quasi-two-dimensional electron layers in tilted magnetic fields B=(B-parallel to, B-perpendicular to), and explain recent data from GaAs/Al(x)Gal(1-x)As double quantum wells. In this system, the electrons are in the two tunnel-split ground sublevels. The cyclotron masses of the two orbits on the Fermi surface have opposite dependences on the in-plane field B-parallel to: one increases monotonically, while the other decreases as a function of B-parallel to, in the regime of interest. As a result, the rungs of one Landau ladder sweep up through the Fermi level, while those of the other Landau ladder sweep down when B-parallel to is increased at a fixed perpendicular field B-perpendicular to. Ridges are obtained in the three-dimensional plots of both R-xx and R-yy and the density of states versus (B-parallel to, B-perpendicular to) due to Fermi-level crossing by the rungs of the Landau ladders. Giant peaks are obtained when two ridges intersect each other. The (B-parallel to, B-perpendicular to) dependence of R-xx as well as theoretical evidence of magnetic breakdown yields good agreement with recent data from GaAs/AlxGa1-xAs double quantum wells. [S0163-1829(98)05027-9]. [References: 27]